The human dbl oncogene, isolated by transfection, has been characterized with respect to its transcribed sequences and the genomic rearrangements present at its termini. Its structure has been compared to dbl sequences present in the lymphoma cells from which it was isolated and also to the dbl proto-oncogene. The mRNA expressed by the human c-fgr proto-oncogene has been isolated and shown to encode the entire fgr protein. Efforts are underway to localize its 5' coding and regulatory sequences in human genomic DNA. Studies on animal lentiviruses have led to the production of the equine infectious anemia virus (EIAV) gag gene precursor in bacteria and the development of sensitive and specific assays for EIAV. Trans-activation of the EIAV LTR was demonstrated and sequences encoding its tat gene have been localized.